Hepatitis A is a liver disease which, while not commonly fatal, can involve many weeks of debilitating illness. It is usually spread by direct contact with an infected indivudal or by contaminated drinking water or food. Recent discoveries have enabled the in vitro propagation of this virus. Titers of the in vitro propagated virus, however, are usually low, i.e., about 2 or less as determined by the immune adherence hemagglutination assay (IAHA).